Polyfunctional organosiloxanes, compositions containing same, and methods for the preparation thereof

Abstract

A polyfunctional organohydrogensiloxane and method for its preparation using a boron containing Lewis acid as catalyst is disclosed. A clustered functional organosiloxane may be prepared by a method comprising functionalizing the polyfunctional organohydrogensiloxane. The polyfunctional organohydrogensiloxane and the clustered functional organosiloxane are useful in curable compositions. The polyfunctional organohydrogensiloxane may be used in a release coating composition. The clustered functional organosiloxane may be used in an adhesive composition.

The invention claimed is: 
     
       1. A clustered functional organosiloxane of unit formula: 
       
         
           
           
               
               
           
         
         where 
       
       subscript n is 2 to 2,000, each subscript d is independently 0 to 995, subscript o′=0 to 100, subscript n′=(o′+1), each R is an independently selected monovalent hydrocarbon group, each R 1  is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups, and each R 8  is a hydrogen atom or a curable group, with the proviso that at least one R 8  per molecule is a curable group other than hydrogen. 
     
     
       2. The clustered functional organosiloxane of  claim 1 , where subscript o′=0 and the clustered functional organosiloxane has formula: 
       
         
           
           
               
               
           
         
       
     
     
       3. The clustered functional organosiloxane of  claim 2 , where each subscript d=0, and the clustered functional organosiloxane has formula: 
       
         
           
           
               
               
           
         
       
     
     
       4. The clustered functional organosiloxane of  claim 1 , where subscript n is 2 to 1,000, each R is an alkyl group of 1 to 6 carbon atoms, and each R 1  is selected from the group consisting of an alkyl group of 1 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, and a halogenated alkyl group of 1 to 20 carbon atoms. 
     
     
       5. The clustered functional organosiloxane of  claim 1 , where subscript n is 5 to 50; each R is methyl; and each R 1  is independently selected from the group consisting of methyl, vinyl, phenyl, and trifluoropropyl. 
     
     
       6. A method for preparing a polyfunctional organohydrogensiloxane comprising:
 1) combining 
 A) a boron containing Lewis acid; 
 B) a hydroxyl terminated polydiorganosiloxane of formula 
 
       
         
           
           
               
               
           
         
       
       subscript n is 2 to 2,000, and each R 1  is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups; and
 C) a polyorganohydrogensiloxane of formula 
 
       
         
           
           
               
               
           
         
       
       where each subscript d is independently 0 to 995, and each R is an independently selected monovalent hydrocarbon group, thereby preparing the product, where the product comprises a polyfunctional organohydrogensiloxane and a by-product comprising H 2 . 
     
     
       7. The method of  claim 6 , where the method is performed at a temperature of 5° C. to 70° C. 
     
     
       8. The method of  claim 6 , where A) the boron containing Lewis acid is a trivalent boron compound with at least one perfluoroaryl group per molecule. 
     
     
       9. The method of  claim 8 , where A) the boron containing Lewis acid is B(C 6 F 5 ) 3 , tris(pentafluorophenyl)borane. 
     
     
       10. The method of  claims 6 , where subscript n is 2 to 1,000, and each R 1  is selected from the group consisting of an alkyl group of 1 to 20 carbon atoms, an alkenyl group of 2 to 20 carbon atoms, an aryl group of 6 to 20 carbon atoms, and a halogenated alkyl group of 1 to 20 carbon atoms. 
     
     
       11. The method of  claims 6 , where C) the polyorganohydrogensiloxane has formula: 
       
         
           
           
               
               
           
         
       
     
     
       12. The method of  claim 11 , where each R is an alkyl group of 1 to 6 carbon atoms. 
     
     
       13. The method of  claims 6 , further comprising recovering the polyfunctional organohydrogensiloxane, wherein the method comprises one or more of: 2) during and/or after step 1), removing the H 2  generated during formation of the polyfunctional organohydrogensiloxane; 3) neutralizing residual boron containing Lewis acid in the organohydrogensiloxane dendrimer and/or 4) removing a particulate. 
     
     
       14. The method of  claim 6 , further comprising:
 combining a) the polyfunctional organohydrogensiloxane, 
 b) a hydrosilylation reaction catalyst, and 
 c) a reactive species having an average, per molecule at least one aliphatically unsaturated group capable of undergoing an addition reaction with a silicon bonded hydrogen atom of starting material b) and further comprising one or more curable groups per molecule; thereby preparing a product comprising a clustered functional organosiloxane. 
 
     
     
       15. The method of  claim 14 , where the reactive species comprises a silane of formula R 4   y SiR 5   (4−y) , where subscript y is 1 to 3, each R 4  is the aliphatically unsaturated group capable of undergoing an addition reaction, and each R 5  is the curable group; thereby preparing a product comprising a clustered-functional polyorganosiloxane dendrimer. 
     
     
       16. The method of  claim 15 , where subscript y=1; each R 4  is independently selected from the group consisting of alkenyl and alkynyl; and each R 5  is independently selected from the group consisting of an organic group containing an acrylate group, an alcohol group, an alkoxy group, an epoxy group, an isocyanate group, a methacrylate group, or a urethane group. 
     
     
       17. The method of  claim 14 , where each aliphatically-unsaturated group is independently selected from the group consisting of alkenyl and alkynyl; and curable group is independently selected from the group consisting of an organic group containing an acrylate group, an alcohol group, an alkoxy group, an epoxy group, an isocyanate group, a methacrylate group, or a urethane group. 
     
     
       18. A curable composition comprising:
 (I) the clustered functional organosiloxane of  claim 1  and 
 (II) a curing agent. 
 
     
     
       19. An adhesive composition comprising:
 A) clustered functional organosiloxane of unit formula: 
 
       
         
           
           
               
               
           
         
       
       where subscript n is 2 to 2,000, each subscript d is independently 0 to 995, subscript o′=0 to 100, subscript n′=(o′+1), each R is an independently selected monovalent hydrocarbon group, each R 1  is independently selected from the group consisting of monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups, and each R 8  is a hydrogen atom or a curable group, with the proviso that at least one R 8  per molecule is a curable group other than hydrogen;
 B) a reactive resin and polymer, 
 C) a condensation reaction catalyst, and 
 D) a free radical initiator; and 
 optionally, one or more additional starting materials selected from the group consisting of E) a dual cure compound, F′) an adhesion promoter, G) a corrosion inhibitor, H) a rheology modifier, I) a drying agent, J) a crosslinker, K) a filler, L) a spacer, M) an acid scavenger, N) a silanol functional polydiorganosiloxane, O ) a fluorescent optical brightener, P) a chain transfer agent, Q) a (methacrylate monomer, R) a poly-alkoxyterminated polydiorganosiloxane, and S) a colorant.